Article
Mechanics
William S. LePage, John A. Shaw, Samantha H. Daly
Summary: The study revealed that crystallographic texture significantly affects the fatigue performance of NiTi sheet, with strong orientation-dependent mechanisms of plasticity, transformation, and twinning on both functional and structural fatigue. Under stress-controlled cycling, tension along textures similar to that of the TD demonstrated better fatigue performance.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2021)
Article
Nanoscience & Nanotechnology
V. V. Shastry, Gaurav Singh, U. Ramamurty
Summary: The study demonstrates that periodic "healing" treatment during fatigue testing of shape memory alloys can effectively extend the fatigue life of the alloy, with 20% of the life elapsed being the optimal treatment time point. Different timing of healing treatment affects the effectiveness of improving fatigue life, indicating irreversible damage has already occurred.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Xiebin Wang, Xiayang Yao, Dominique Schryvers, Bert Verlinden, Guilong Wang, Guoqun Zhao, Jan Van Humbeeck, Sergey Kustov
Summary: This work reports anomalous phenomena in superelastic cycling of NiTi shape memory alloys near the temperature border, including higher critical stress, plateau stress changes, and transition from good superelasticity to fully irreversible strain, which may be caused by defects generated during the first superelastic cycle near the border impeding stress-induced martensitic transformations.
SCRIPTA MATERIALIA
(2021)
Article
Chemistry, Physical
Mohammadreza Nematollahi, Sayed Ehsan Saghaian, Keyvan Safaei, Parisa Bayati, Paola Bassani, Carlo Biffi, Ausonio Tuissi, Haluk Karaca, Mohammad Elahinia
Summary: This study investigates the microstructure and shape memory properties of laser powder bed fusion NiTi parts fabricated in different building orientations. The research reveals that different orientations lead to anisotropic compression-tension behaviors, with texture variations impacting the mechanical performance of the samples.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Junyu Chen, Liping Lei, Gang Fang
Summary: The study investigates the effects of grain size on the temperature-dependent elastocaloric cooling performance of NiTi. It shows that refining the grain size improves the thermal stability of superelasticity but results in a trade-off between cooling temperature drop and effective working temperature span. By adjusting the grain size, a balance can be achieved between cooling efficiency and performance.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Saeed Ataollahi, Mohammad J. Mahtabi
Summary: In this study, molecular dynamics simulations were used to investigate stress-induced and temperature-induced phase transformations in NiTi shape memory alloy with Ni4Ti3 precipitate. The results show that the precipitate has a pronounced effect on the superelastic behavior in <100 > loading directions.
MATERIALS TODAY COMMUNICATIONS
(2021)
Review
Materials Science, Multidisciplinary
Woo-Chul Kim, Ka-Ram Lim, Won-Tae Kim, Eun-Soo Park, Do-Hyang Kim
Summary: This paper introduces a new alloy concept based on NiTi alloys, with both glass forming ability and shape memory characteristics. By suppressing the formation of brittle intermetallic compounds, the physical properties of shape memory alloys fabricated using glass precursor can be maximized. The structure and properties of multicomponent SMA systems are also discussed.
PROGRESS IN MATERIALS SCIENCE
(2022)
Review
Materials Science, Multidisciplinary
Woo-Chul Kim, Ka-Ram Lim, Won-Tae Kim, Eun-Soo Park, Do-Hyang Kim
Summary: A new concept has been introduced for an alloy with both glass forming ability and shape memory characteristics, which can enhance the physical properties of shape memory alloys by suppressing the formation of brittle intermetallic compounds and enabling the formation of nanocrystalline structure. The glass precursor is not only suitable for small-sized devices but also allows for production of intricate geometry through thermoplastic forming, with shape memory effect or superelasticity manifested after crystallization. The study reviews typical NiTi-based SMAs and multicomponent SMAs fabricated using glass precursor, discussing the effects of quaternary doping and the properties of multicomponent SMA systems.
PROGRESS IN MATERIALS SCIENCE
(2021)
Article
Engineering, Mechanical
Peng Chen, Xiaorong Cai, Yunfan Liu, Zhengxiong Wang, Mingjiang Jin, Xuejun Jin
Summary: The structural fatigue life of nanocrystalline NiTi wires was improved by stress-controlled mechanical training, with the improvement increasing with grain size. The untrained samples showed a decrease in structural fatigue life with increased grain size. However, after training, the structural fatigue life increased with grain size due to the generation and movement of dislocations during training, which improved the orientation intensity of (1 1 1) texture parallel to the drawn direction. The reduction of fatigue striation spacing indicated training-induced plastic deformation and the enhanced (1 1 1) texture hindered crack propagation.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Nanoscience & Nanotechnology
Binqiang Li, Liang Wang, Binbin Wang, Donghai Li, J. P. Oliveira, Ran Cui, Jianxin Yu, Liangshun Luo, Ruirun Chen, Yanqing Su, Jingjie Guo, Hengzhi Fu
Summary: In this study, NiTi shape memory alloy parts were additively manufactured using EBF3. The effects of different processing parameters on the forming quality and properties were investigated. The optimized deposit exhibited the best comprehensive properties, and the relationship between martensitic transformation behavior and plastic deformation during superelastic deformation was discussed.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Mechanics
Dongjie Jiang, Yao Xiao
Summary: A new constitutive model for superelastic NiTi is proposed in this study, incorporating intrinsic material instability and thermomechanical coupling. Through simulations of global and local thermomechanical responses, it is found that the grain size significantly affects the deformation characteristics of NiTi.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
Ali Rasouli, Homam Naffakh-Moosavy
Summary: NiTi shape memory alloy (SMA) offers various industrial applications, but the formation of intermetallic compounds in the joint with Ni20Cr alloy leads to reduced mechanical properties and increased hardness. Post-weld heat treatment can alter the microstructure and mechanical properties of the welded joint and produce NiTi intermetallic phase.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Engineering, Mechanical
Lakhindra Marandi, Indrani Sen
Summary: This study carefully examines the in-vitro performance of the NiTi system under conditions such as corrosion, bio-fluids, fatigue mean-stress, stress-ratio, and functional-fatigue. The alloy shows excellent pseudoelastic plateau-strain and optimal combination of ultimate tensile strength and ductility, providing valuable insights for its biomedical application.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Engineering, Mechanical
Yanqiu Zhang, Shuyong Jiang, Guilong Zhao, Kairui Guo
Summary: The mechanical behavior and phase transformation of nanocrystalline NiTi shape memory alloy under complex stress states were investigated using molecular dynamics (MD) simulation. Tension-compression asymmetry was observed in terms of transformation strain, critical transformation stress, dissipation energy density, martensite variant, and martensite domain. A new transformation yield criterion based on the Bouvet and Patoor criteria was proposed to accurately describe the transformation stress anisotropy in complex stress states.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Nanoscience & Nanotechnology
Peng Chen, Yunfan Liu, Na Min, Meimei Wang, Xiaorong Cai, Mingjiang Jin, Xuejun Jin
Summary: In this study, an excellent two-way shape memory effect (TWSME) with large magnitude and small cyclic degradation of NiTi wires is achieved by combining martensite deformation and nanocrystallization. The wires exhibit a maximum TWSME strain of 7.37% after being pre-deformed to 11% and maintain a stable strain of 6.88% after 20 cycles. The excellent TWSME is attributed to the dislocation structures induced by martensite deformation and the nanocrystalline strengthened matrix.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Taiwu Yu, Yipeng Gao, Lee Casalena, Peter Anderson, Michael Mills, Yunzhi Wang
Summary: The study investigates the influence of precipitates on the properties of NiTi-based high temperature shape memory alloys, revealing that spatially inhomogeneous stress and concentration fields have dominant effects on the martensitic transformation start temperature M-s at different aging times.
Article
Materials Science, Multidisciplinary
Rongpei Shi, Yipeng Gao, Dian Li, Wenrui Zhao, Yufeng Zheng
Summary: Metastable beta-titanium alloys are widely used in various industries due to their high specific strength, superior corrosion resistance, and excellent biocompatibility. Recent studies have obtained fundamental insights in designing strategies through exploring different solid-state phase transformation and deformation pathways, indicating promising future research directions for the development of these alloys.
ADVANCED ENGINEERING MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Nan Xia, Cheng Wang, Yipeng Gao, Zhen-Ming Hua, Chen-Yi Ma, Chun-Feng Du, Hang Zhang, Hong-Min Zhang, Mei-Xuan Li, Min Zha, Hui-Yuan Wang
Summary: In this study, a Mg?1Zn?0.2Zr (ZK10) alloy sheet was prepared by multi-pass hot rolling and annealing, with the addition of dilute Ca to tailor the basal texture and reduce plastic anisotropy. Microstructural characterizations showed improved ductility due to the occurrence of pyramidal c+a slip in the deformed alloys. This work may offer a new strategy for developing wrought Mg alloys with enhanced ductility.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Miaomiao Jin, Yipeng Gao, Chao Jiang, Jian Gan
Summary: The migration of defects in U-Mo alloys and pure metals is found to be composition-dependent, with point defect migration strongly correlated and mediated by minor atoms in alloys. Interstitial dumbbells and vacancies migrate through preferred paths, with vacancies and interstitials showing comparable diffusivity in U-rich systems. Defect diffusivity can be adjusted based on alloy composition.
JOURNAL OF NUCLEAR MATERIALS
(2021)
Article
Multidisciplinary Sciences
Miaomiao Jin, Yipeng Gao, Yongfeng Zhang, Chao Jiang, Jian Gan
Summary: This study elaborates on the bubble growth process in Cu through atomistic modeling, showing that bubble generation can significantly degrade material performance. The formation and development of bubbles involve multiple steps, potentially leading to the formation of a self-organized bubble superlattice.
SCIENTIFIC REPORTS
(2021)
Article
Engineering, Mechanical
Min Zha, Hui-Yuan Wang, Chunfeng Du, Yipeng Gao, Zhen-Ming Hua, Cheng Wang
Summary: Superplastic forming is crucial for producing complex-shaped components in Mg-alloys, especially in high-alloyed systems. However, stabilizing small grains and facilitating grain boundary sliding in low-alloyed systems is challenging due to insufficient precipitates. Through a unique design strategy involving solute segregation, an Mg-1Zn-0.2Ca-0.2Zr-0.1Ag (wt.%) alloy achieved ~450% superplastic strain by absorbing intragranular dislocations through stress-driven grain boundary migration mediated by disclination-dislocation reactions. This study provides insights into the relationship between microstructural defects evolution and strain accommodation during superplastic deformation, shedding light on the nature of superplasticity mechanism.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Materials Science, Multidisciplinary
Zhen-Ming Hua, Cheng Wang, Tian-Shuai Wang, Chunfeng Du, Shen-Bao Jin, Gang Sha, Yipeng Gao, Hai -Long Jia, Min Zha, Hui -Yuan Wang
Summary: This study demonstrates that cyclic deformation of a Mg alloy at room temperature can significantly increase the yield strength while only slightly reducing the elongation to failure. The strength improvement is mainly attributed to the formation of high-density solute clusters. This work provides new insights into the strengthening mechanisms and has important implications for the development of Mg alloys with high strength-ductility synergy.
Article
Materials Science, Multidisciplinary
Yi-Jia Li, Mei-Xuan Li, Zhen-Ming Hua, Bing-Yu Wang, Yipeng Gao, Hui-Yuan Wang
Summary: The effect of Al on microstructure and corrosion behavior of cast Mg-2Zn-xAl-0.5Ca (x = 0, 0.5, 1.0, 2.0 wt%) alloys is investigated. The addition of 0.5 wt% Al leads to the lowest corrosion rate of 4 mm/y. This is attributed to the decreased cathodic activity of Ca2Mg6Zn3 phase due to Al doping and the refined intermetallics resulting from Al alloying, which reduce pitting corrosion. Additionally, the finer grains enhance the barrier effect at grain boundaries, effectively confining corrosion propagation. The formation of Al2O3 reinforces the surface film. The optimum Al content is determined to be 0.5-1.0%, which provides the alloy with admirable corrosion resistance and high ultimate tensile strength.
Article
Materials Science, Multidisciplinary
Chunfeng Du, Yipeng Gao, Min Zha, Cheng Wang, Hailong Jia, Hui-Yuan Wang
Summary: Grain boundary mediated plasticity, such as grain rotation and grain boundary sliding, is crucial in determining the deformation behavior of polycrystals, especially in nanocrystalline metals or plastic deformation at high temperatures. However, the mechanism of deformation-induced grain rotation has not been well understood due to the lack of a theoretical framework. This study introduces a disclination-based description and shows that crystal rotation can be conveniently captured through the characteristic rotational vector of a disclination. The topological defect theory provides a framework for treating grain boundary mediated plasticity as topological reactions between dislocations and disclinations, enabling accurate predictions of grain/subgrain rotation using the reformulated Frank-Bilby equation.
Article
Materials Science, Multidisciplinary
Bing-Yu Wang, Mei-Xuan Li, Yi-Jia Li, Yu-Fei Wang, Yipeng Gao, Hui-Yuan Wang
Summary: Lean Mg-1.2Zn-0.3Ca-0.3Al-xMn (x = 0.25, 0.38, 0.5 wt%) alloys with different Al/Mn ratios were prepared using twin-roll casting technique. The formation of rhombohedral Al8Mn5 or cubic beta-Mn depended on the Al/Mn ratio. The alloy with Al/Mn>1.6 exhibited the lowest average corrosion rate (4.55 mm y-1) due to the lower Volta potential of Al8Mn5 compared to beta-Mn. The presence of fine Al8Mn5 weakened micro-galvanic corrosion and reduced stress concentration, resulting in admirable corrosion resistance and mechanical properties (UTS: -266 MPa, YS: -193 MPa, EF: -20%) for the alloy with Al/Mn>1.6.
Article
Engineering, Mechanical
Yipeng Gao, Lei Zhao, Min Zha, Chun-Feng Du, Zhen-Ming Hua, Kai Guan, Hui-Yuan Wang
Summary: Twinning-induced plasticity is critical for hexagonal close-packed metals such as Mg and Ti, due to their lack of independent slip systems. This study reveals a new extension twinning mode {11 (2) over bar6} in Mg-alloys, in addition to the previously identified {10 (1) over bar2} type twin. The formation of {11 (2) over bar6} twin is explained through reactions between disclinations and {10 (1) over bar2} twins. The {11 (2) over bar6} twins can provide significant tensile and compressive strains along specific directions, and their formation mechanisms are validated through experiments and simulations.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Engineering, Mechanical
Yumeng Zhang, Yixuan Hu, Huabing Li, Yipeng Gao, Yabo Wang, Hao Feng, Yao Shen, Kolan Madhav Reddy, Zhouhua Jiang, Xiaodong Wang, Mingwei Chen
Summary: Delicate control of detrimental brittle AlN precipitates is essential for enhancing the applications of high nitrogen steels. Stacking faults in nano-sized AlN precipitates can be activated by martensitic transformation, which allows for accommodating the transformation stresses and strains at the precipitate/matrix interfaces. This finding provides new guidelines for mitigating the harmful effects of AlN precipitates in high nitrogen steels and reducing production costs.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Engineering, Mechanical
Tong Wang, Min Zha, Yipeng Gao, Si-Qing Wang, Hai -Long Jia, Cheng Wang, Hui-Yuan Wang
Summary: A novel multiscale hetero-structure was prepared in Mg-9Al-1Zn alloy, which exhibited high strength and high ductility. Diversified strain accommodation mechanisms were induced by the strain incompatibilities near hetero-interfaces in the multiscale hetero-structure. Multiple deformation modes were activated substantially, effectively relaxing local stress concentration and achieving stable plastic flow at a high-stress state, which improved strain-hardening ability and strength-ductility synergy.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Materials Science, Multidisciplinary
Jia-Sheng Li, Mei-Xuan Li, Zhen-Ming Hua, Yuan-Ting Mo, Kai Guan, Min Zha, Yipeng Gao, Hui-Yuan Wang
Summary: The corrosion resistance of Mg-0.6Al-0.5Mn-0.2Ca alloy sheet can be improved by micro-alloying with 0.3 wt.% Ce, and the strength can be augmented after aging treatment. The addition of Ce decreases the activity of cathodic phases and forms a protective surface film, contributing to the high strength and satisfactory ductility of the alloy.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)